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Thyroid Diseases

Cortisol Readings and Diagnosing Cushing's Syndrome

11/05/2007

Question:

I have sought many doctors for my 20 year old daughter. We have been to an endocrynologist but found no answers to her many symptoms. The last doctor was a hormone balancing doctor. He said her cortisol a m reading was 37 and should be around 25. He thought it was due to stress and now is on prozac and many supplements to reduce this level. My question is how high does a 8 am reading need to be to diagnose Cushings?

Answer:

Cortisol is secreted in pulses, and you really can't attach too much significance to a single blood cortisol level drawn in the morning. The cortisol of 37 is high, but I would be uncomfortable basing any treatment decisions about stress and Prozac on such a blood level. Cushing's Syndrome is not diagnosed with single serum cortisol levels. It is diagnosed with 24 hour urinary free cortisols, salivary cortisols collected at midnight, or by looking at the response of serum cortisol to suppression with a medication called "dexamethasone."

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Response by:

Thomas A Murphy, MD, FACP, FACE Thomas A Murphy, MD, FACP, FACE
Associate Professor of Medicine
School of Medicine
Case Western Reserve University